MQTT Ping failed

STATE: IP STATUS
AT+CIPSTART="TCP","v1b82961.ala.us-east-1.emqxsl.com","8883"

OK
AT+CIPSTATUS

OK

STATE: TCP CONNECTING

CONNECT
MQTT.TCP_Flag = True
pingSent = true
Ping failed

cany you please help me to connect EMQX MQTT sever using CA certification 
